Connecting device of tent poles

ABSTRACT

A connecting device of tent poles has a first connecting pipe including one end having an inner diameter corresponding to an outer diameter of one tent pole and the other end forming a widened part having a widened diameter compared to one end when connecting a pair of tent poles. An end of the one tent pole is inserted and fixed in one end of the connecting pipe and an end of the other tent pole is connected to the widened part. According to the invention, it is possible to reduce a weight of the tent poles and to prevent the damage of the connecting device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims all benefits of Korean Patent Application No. 2005-15287 filed on Feb. 24, 2005 in the Korean Intellectual Property Office, the disclosures of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a connecting device of tent poles, and more particularly to a connecting device of tent poles capable of solving weakness of a connected part of fiber reinforced plastic (FRP) tent poles while reducing a weight of the FRP tent poles and allowing a cross section of the FRP tent pole not to be exposed, when the FRP tent poles are connected by a connecting pipe.

2. Background of the Related Art

In general, a tent consists of waterproof fabric and a plurality of tent poles, so that it provides a user with a space in which the user can temporarily reside out of doors during the mountain climbing or camping. The tent poles are assembled with each other, thereby forming a tent having various shapes. In this case, the tent pole is a frame for forming a space in the tent by unfolding the waterproof fabric, mostly formed into a cylindrical pipe shape and made of high strength aluminum tube or FRP tube. The high strength aluminum tube is light and has a fine appearance. However, since it is high in price, it is used for a high quality tent. To the contrary, the FRP tube is low in price and thus widely used.

FIG. 1 shows a connecting device of tent poles consisting of FRP tubes according to the prior art. Referring to FIG. 1, a tent pole 4 is inserted into one end of a connecting pipe 2 and then fixed to it by an adhesive 8 and the like. Another tent pole 6 is inserted into the other end of the connecting pipe 2 so that the tent poles 4, 6 are connected to each other by the connecting pole 2. Generally, the tent poles 4, 6 are made of FRP having a very excellent elastic force and the connecting pipe 2 is made of aluminum and cupronickel and the like having a relatively low elastic force.

The connected tent poles 4, 6 are bended into an arch shape to form a frame of the tent. In this case, as shown in FIG. 2, a bending stress is applied to the connected part of the tent poles 4, 6. When the bending stress is applied, load is applied to the tent poles 4, 6 in an arrow (A) direction. As a result of that, fracture often occurs at the tent poles 4, 6 contacting with the ends of the connecting pipe 2. In addition, the FRP tent poles 4, 6 are typically made by a draw molding method. During the manufacturing, it is difficult to precisely control a size of an outer diameter of the tent pole, like a metal. Accordingly, gaps between the connecting pipe 2 and the tent poles 4, 6 are inevitably widened. Thereby, the load is applied much more in the arrow (A) direction, so that the FRP tent poles 4, 6 are easily damaged.

In the mean time, the FRP is a composite material comprising a plastic having tension, impact resistance and corrosion resistance reinforced with a glass fiber and the like. As shown in FIG. 2, when the FRP is cut to manufacture the FRP tent poles 4, 6, the glass fiber of the FRP cross section is exposed. Accordingly, when the glass fiber contacts to a skin of a user, a cutaneous disorder may be caused.

Accordingly, continuous research and development have been carried out so as to solve the problems occurring in the prior art. The invention is made under such technical background.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been made to solve the above problems. An object of the present invention is to connect FRP tent poles with a connecting pipe made of high strength aluminum having a high elastic force, thereby preventing the FRP tent poles from being damaged at a connected part thereof and reducing a whole weight of the connected tent poles.

In order to achieve the above object, there is provided a connecting device of tent poles comprising a first connecting pipe including one end having an inner diameter corresponding to an outer diameter of one tent pole and the other end forming a widened part having a widened diameter compared to one end wherein an end of the one tent pole is inserted and fixed in one end of the connecting pipe and an end of the other tent pole is connected to the widened part.

According to an embodiment of the invention, the connecting device may further comprise a second connecting pipe including one end having an inner diameter corresponding to an outer diameter of the other tent pole and the other end forming a reduced part having a reduced outer diameter compared to one end so as to correspond to an inner diameter of the widened part of the first connecting pipe wherein an end of the other tent pole is inserted and fixed in one end of the second connecting pipe and the reduced part is inserted and fixed in the widened part of the first connecting pipe.

According to an embodiment of the invention, the one tent pole may have a diameter smaller than the other tent pole and the widened part of the first connecting pipe may have an inner diameter corresponding to an outer diameter of the other tent pole, and an end of the other tent pole is directly connected to the widened part of the first connecting pipe.

According to an embodiment of the invention, the one tent pole may have a diameter smaller than the other tent pole and the connecting device may further comprise a second connecting pipe including one end having an inner diameter corresponding to an outer diameter of the other tent pole and the other end forming a reduced part having a diameter reduced to be equal to the widened part of the first connecting pipe, and a third connecting pipe having both ends inserted and fixed in the widened part of the first connecting pipe and the reduced part of the second connecting pipe, respectively.

According to an embodiment of the invention, the tent poles may have a diameter equal to each other, the end of the other tent pole may be formed with a widened part having a diameter widened to be equal to the widened part of the first connecting pipe and the connecting device may further comprise a third connecting pipe having both ends inserted and fixed in the widened part of the first connecting pipe and the widened part of the other tent pole, respectively.

According to an embodiment of the invention, the one tent pole may have a diameter smaller than that of the other tent pole, the end of the other tent pole may be formed with a reduced part having a diameter reduced to be equal to the widened part of the first connecting pipe and the connecting device may further comprise a third connecting pipe having both ends inserted and fixed in the widened part of the first connecting pipe and the reduced part of the other tent pole, respectively.

According to an embodiment of the invention, a bending rigidity of the reduced part of the second connecting pipe may be 60% or more of a bending rigidity of the widened part of the first connecting pipe, the tent pole may be made of fiber reinforced plastic (FRP) or carbon, and the connecting pipe may be made of high strength aluminum.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a sectional view showing a connecting device of tent poles according to the prior art;

FIG. 2 is a sectional view showing a state that a bending stress is applied to the connecting device of tent poles shown in FIG. 1;

FIG. 3 is a perspective view showing a connecting device of tent poles according to a preferred embodiment of the invention;

FIG. 4 is a section view taken along a line IV-IV′ of FIG. 3 (although a first connecting pipe and a second connecting pipe are not connected to each other, they are shown to be connected to each other in FIG. 4 for convenient explanations);

FIGS. 5 and 6 are sectional views showing connecting devices of tent poles according to other preferred embodiments of the invention for connecting tent poles having different diameters; and

FIGS. 7 to 9 are sectional views showing connecting devices of tent poles according to still other preferred embodiments of the invention for connecting tent poles made of different materials.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

FIG. 3 is a perspective view sowing a connecting device of tent poles according to an embodiment of the invention and FIG. 4 is a sectional view taken along a line IV-IV′ of FIG. 3. Although it is shown in FIG. 3 that a first connecting pipe 13 and a second connecting pipe 17 are not connected, they are shown to be connected in FIG. 4 for convenient descriptions.

Referring to FIGS. 3 and 4, in the connecting device of tent poles according to the invention, ends of a pair of tent poles 12, 16 to be connected to each other, which ends are opposite, are inserted and fixed in the first connecting pipe 13 and the second connecting pipe 17, respectively. One end of the tent pole 12 is inserted and fixed in one end of the first connecting pipe 13 and a widened part 14 having a diameter larger than the one end is formed on the other end of the first connecting pipe 13. One end of the tent pole 16 is inserted and fixed in one end of the second connecting pipe 17 and a reduced part 18 having an outer diameter corresponding to an inner diameter of the widened part 14 of the first connecting pipe 13 is formed on the other end of the second connecting pipe 17. The reduced part 18 of the second connecting pipe 17 is inserted and fixed in the widened part 14 of the first connecting pipe 13.

The tent poles 12, 16 are made of a material having light weight and excellent bending rigidity and being inexpensive. Preferably, the tent poles 12, 16 are made into a tube shape using fiber reinforced plastic (FRP) or carbon.

The connecting pipes 13, 17 are made of a material having high durability and elastic force compared to metal such as soft aluminum or cupronickel which is conventionally used. Preferably, the connecting pipes 13, 17 are made of high strength aluminum. If the connecting pipes 13, 17 made of high strength aluminum having an excellent elastic force are used, it is possible to prevent the tent poles 12, 16 from being damaged when the bending stress is applied to a connected part of the tent poles 12, 16 since it is possible to sufficiently reduce the load applying to the tent poles 12, 16 at ends of the connecting pipes 13, 17, contrary to the metal connecting pipes according to the prior art.

In the mean time, an inertia moment in the tube shape is represented by a following formula 1. I=MR ²  [formula 1]

where I=inertia moment, M=mass, and R=inner radius of the tube. In the tube shape, the larger the radius is, the higher the inertia moment is.

Accordingly, the connecting pipe 13 having the widened part 14 has an inertia moment larger than the connecting pipe having no widened part as the diameter increases. As the inertia moment increases, the bending moment also increases. Thereby, when the tent poles 12, 16 are connected by the connecting pipe 13 having the widened part 14, it is possible to prevent the connecting pipe 13 from being damaged.

Referring to FIGS. 3 and 4 again, one end of the tent pole 12 is inserted and fixed in one end of the first connecting pipe 13 and the widened part 14 is formed on the other end of the first connecting pipe 13. When the tent pole is made of FRP, it is difficult to precisely control and manufacture the outer diameter. Accordingly, a gap between the first connecting pipe 13 and the tent pole 12 is maintained to be about 0.2˜0.3 mm and filled with an adhesive 15 so that one end of the tent pole 12 is firmly fixed in the first connecting pipe 13. Since the end of the first connecting pipe 13 is made to have an inner diameter corresponding to an outer diameter of the tent pole 12 to be inserted, it is possible to connect the tent pole 12 having diverse outer diameters using the first connecting pipe 13.

Contrary to the first connecting pipe 13, one end of the tent pole 16 is inserted and fixed in one end of the second connecting pipe 17 and a reduced part 18 is formed on the other end of the second connecting pipe 17. The one end of the second connecting pipe 17 is made to have an inner diameter corresponding to an outer diameter of the tent pole 16. Likewise the first connecting pipe 13, a gap between the second connecting pipe 17 and the tent pole 16 is filled with an adhesive 19, so that one end of the tent pole 16 is firmly fixed in the second connecting pipe 17.

After the ends of the tent poles 12, 16 are inserted and fixed in the first and second connecting pipes 13, 17, respectively, the reduced part 18 of the second connecting pipe 17 is inserted into the widened part 14 of the first connecting pipe 13 so that the tent poles 12, 16 are connected to each other. Since the first and second connecting pipes 13, 17 are made of high strength aluminum, it is possible to make the connecting pipes thin while having a high bending rigidity. Accordingly, it is possible to reduce the load applying to each of the tent poles 12, 16 by making the first and second connecting pipes 13, 17 thin. Thus, the damage of the tent poles 12, 16 can be prevented and a weight of the connected part of the tent poles 12, 16 can be reduced. A gap between the widened part 14 of the first connecting pipe 13 and the reduced part 18 of the second connecting pipe 17 is maintained to be about 0.1 mm for ease assembly.

If each of the tent poles 12, 16 is assembled according to the above process, it is possible to connect the tent poles 12, 16 having different diameters. Specifically, even when the diameters of the tent poles 12, 16 are different from each other, if inner diameters of ends of the first and second connecting pipes 13, 17 are made to correspond to each of outer diameters of the tent poles 12, 16, it is possible to connect the tent poles 12, 16 by inserting the reduced part 18 of the second connecting pipe 17 into the widened part 14 of the first connecting pipe 13.

In addition, since the connecting pipes 13, 17 are provided to the ends of the tent poles 12, 16, the cross sections of the tent poles 12, 16 are not exposed. Accordingly, even when the tent poles 12, 16 are made of FRP, it is possible to prevent a user from contacting to glass fibers of the cross sections of the FRP tent poles.

FIGS. 5 and 6 show connecting devices of tent poles having different diameters according to other preferred embodiments of the invention.

The embodiment shown in FIG. 5 is different from the embodiment of FIG. 4 in that a pair of tent poles 22, 26 have diameters different from each other, and one end of the tent pole 26 is directly connected to a widened part 25 of a first connecting pipe 25.

Referring to FIG. 5, in this embodiment, one end of the tent pole 22 having a smaller diameter is inserted into one end of a first connecting pipe 21 and then fixed with an adhesive and the like. Meanwhile, a widened part 25 having an inner diameter corresponding to outer diameter of one end of the tent pole 26 having a larger diameter is formed on the other end of the first connecting pipe 21. Therefore, one end of the tent pole 26 having a larger diameter is inserted and fixed in the widened part 25 of the first connecting pipe 21 fixed on one end of the tent pole 22 having a smaller diameter.

Meanwhile, one end of the tent pole 22 having a smaller diameter is inserted into the first connecting pipe 21 so that one end of the tent pole 22 is reached to the widened part 25 formed on the other end of the first connecting pipe 21. Accordingly, when one end of the tent pole 26 having a larger diameter is inserted into the widened part 25 of the first connecting pipe 21, one end of the tent pole 22 prevent the tent pole 26 from being inserted over the widened part 25 of the first connecting pipe 21.

Preferably the widened part 25 of the first connecting pipe 21 is made to have an inner diameter larger than the outer diameter of the tent pole 26 having larger diameter by about 0.1 mm so that one end of the tent pole 26 having a larger diameter can be easily inserted into the widened part 25 of the first connecting pipe 21.

The embodiment shown in FIG. 6 is different from the embodiment of FIG. 4 in that a widened part 24 of a first connecting pipe 23 has a diameter equal to that of a reduced part 28 of a second connecting pipe 27, and both ends of a third connecting pipe 30 are inserted into the widened part 24 of the first connecting pipe 23 and the reduced part 28 of the second connecting pipe 27, respectively.

Referring to FIG. 6, in this embodiment, a pair of tent poles 22, 26 to be connected to each other have diameters different from each other. One end of the tent pole 22 having a smaller diameter is inserted and fixed in one end of the first connecting pipe 23 and the widened part 24 having a diameter larger than that of the one end is formed on the other end of the first connecting pipe 23. One end of the tent pole 26 having a larger diameter is inserted and fixed in one end of the second connecting pipe 27 and the reduced part 28 having a diameter equal to that of the widened part 24 of the first connecting pipe 23 is formed on the other end of the second connecting pipe 27. Both ends of the third connecting pipe 30 have outer diameters corresponding to an inner diameter of the widened part 24 of the first connecting pipe 23 and an inner diameter of the reduced part 28 of the second connecting pipe 27, and are inserted and fixed in the widened part 24 of the first connecting pipe 23 and the reduced part 28 of the second connecting pipe 27, respectively.

The gaps between each of the tent poles 22, 26 and the first and second connecting pipes 23, 27 are filled with adhesives and each of the tent poles 22, 26 and the first and second connecting pipes 23, 27 are strongly connected with the adhesives.

As described above, the widened part 24 of the first connecting pipe 23 and the reduced part 28 of the second connecting pipe 27 are made to have an equal diameter. The third connecting pipe 30 are made to have an outer diameter equal to the inner diameter of the widened part 24 of the first connecting pipe 23 or the reduced part 28 of the second connecting pipe 27. Preferably the third connecting pipe 30 are made to have an outer diameter smaller than the inner diameter by about 0.1 mm so that the third connecting pipe 30 can be easily inserted into the widened part 24 of the first connecting pipe 23 and the reduced part 28 of the second connecting pipe 27.

Both ends of the third connecting pipe 30 are inserted into the widened part 24 of the first connecting pipe 23 and the reduced part 28 of the second connecting pipe 27, respectively. The third connecting pipe 30 is fixed with an adhesive (not shown) at one of the widened part 24 of the first connecting pipe 23 and the reduced part 28 of the second connecting pipe 27 into which the ends of the third connecting pipe 30 are inserted.

In the mean time, in the embodiments shown in FIGS. 3 and 6, it is preferred that bending rigidities of the reduced parts 18, 28 of the second connecting pipes 17, 27 are 60% or more of bending rigidities of the widened parts 14, 24 of the first connecting pipes 13, 23. If the bending rigidities of the reduced parts 18, 28 of the second connecting pipes 17, 27 are less than 60% of bending rigidities of the widened parts 14, 24 of the first connecting pipes 13, 23, the reduced parts 18, 28 of the second connecting pipes 17, 27 may be damaged when the second connecting pipes 17, 27 and the first connecting pipes 13, 23 are connected and the bending stress is applied to the connected part.

FIGS. 7 to 9 show connecting devices of tent poles 42, 52 made of FRP or carbon and tent poles 46, 56 made of other metals such as high strength aluminum. FIG. 7 shows a connecting device of tent poles 42, 46 having a same diameter and FIGS. 8 and 9 show connecting devices of tent poles 52, 56 having different diameters.

Referring to FIG. 7, one end of the tent pole 42 made of FRP or carbon is inserted and fixed in one end of a first connecting pipe 43. A widened part 44 having a diameter larger than that of the one end is formed on the other end of the first connecting pipe 43. On one end of the tent pole 46 is formed with a widened part 47 having a diameter equal to the widened part 44 of the first connecting part 43. Both ends of a third connecting pipe 48 having outer diameters corresponding to the inner diameters of the widened part 44 of the first connecting pipe 43 and the widened part 47 of the tent pole 46 are inserted and fixed in the widened part 44 of the first connecting pipe 43 and the widened part 47 of the tent pole 46, respectively.

In the mean time, the end of the tent pole 42 is firmly fixed to the first connecting pipe 43 with an adhesive. The third connecting pipe 48 has an outer diameter equal to the inner diameters of the widened part 44 of the first connecting pipe 43 and the widened part 47 of the tent pole 46. Preferably, the third connecting pipe 48 has an outer diameter smaller than the inner diameters by about 0.1 mm so that it can be easily inserted into the widened part 44 of the first connecting pipe 43 and the widened part 47 of the tent pole 46.

The both ends of the third connecting pipe 48 are inserted into the widened part 44 of the first connecting pipe 43 and the widened part 47 of the tent pole 46, respectively. The third connecting pipe 48 is fixed with an adhesive (not shown) at one of the widened part 44 of the first connecting pipe 43 and the widened part 47 of the tent pole 46 into which the ends of the third connecting pipe are inserted.

FIGS. 8 and 9 show connecting devices of tent poles 52, 56, 59 having different diameters and materials, which are connected to each other.

The embodiment in FIG. 8 is different from the embodiment shown in FIG. 7 in that a widened part is not formed on one end of the tent pole 59 made of high strength aluminum, and the tent pole 59 made of high strength aluminum is directly connected to a first connecting pipe 51 without the third connecting pipe 48.

Referring to FIG. 8, in this embodiment, one end of the tent pole 52 made of FRP or carbon and having a smaller diameter is inserted into one end of a first connecting pipe 51 and then fixed with an adhesive and the like. Meanwhile, a widened part 55 having an inner diameter corresponding to outer diameter of one end of the tent pole 59 made of high strength aluminum and having a larger diameter is formed on the other end of the first connecting pipe 51. Therefore, one end of the tent pole 59 made of high strength aluminum and having a larger diameter is inserted and fixed in the widened part 55 of the first connecting pipe 51 fixed on one end of the tent pole 52 made of FRP or carbon and having a smaller diameter.

Meanwhile, one end of the tent pole 52 having a smaller diameter is inserted into the first connecting pipe 51 so that one end of the tent pole 52 is reached to the widened part 55 formed on the other end of the first connecting pipe 51. Accordingly, when one end of the tent pole 59 having a larger diameter is inserted into the widened part 55 of the first connecting pipe 51, one end of the tent pole 52 prevent the tent pole 59 from being inserted over the widened part 55 of the first connecting pipe 51.

Preferably the widened part 55 of the first connecting pipe 51 is made to have an inner diameter larger than the outer diameter of the tent pole 59 having a larger diameter by about 0.1 mm so that one end of the tent pole 59 having a larger diameter can be easily inserted into the widened part 55 of the first connecting pipe 51.

The embodiment in FIG. 9 is different from the embodiment shown in FIG. 7 in that a reduced part 57 is formed on one end of the tent pole 56. Hereinafter, the difference will be specifically explained.

Referring to FIG. 9, according to this embodiment, a pair of tent poles 52, 56 to be connected have different diameters. One end of the tent pole 52 having a smaller diameter and made of FRP or carbon is inserted into one end of a first connecting pipe 53 and then fixed with an adhesive and the like. The other end of the first connecting pipe 53 is formed with a widened part 54 having a diameter larger than the one end. One end of the tent pole 56 having a larger diameter is formed with a reduced part 57 having a diameter equal to the diameter of the widened part 54 of the first connecting pipe 53. Both ends of a third connecting pipe 58 having outer diameters corresponding to inner diameters of the widened part 54 of the first connecting pipe 53 and the reduced part 57 of the tent pole 56 are inserted and fixed in the widened part 54 of the first connecting pipe 53 and the reduced part 57 of the tent pole 56, respectively.

As described above, according to the invention, the tent poles are connected to each other by the connecting pipe made of high strength aluminum having high durability and elastic force. Accordingly, it is possible to prevent the damage of the connecting pipe to the utmost even when the bending stress is applied to the connecting pipe.

In addition, according to the invention, the connecting pipe is made of high strength aluminum, contrary to the connecting pipe made of aluminum or cupronickel according to the prior art. Accordingly, the connecting pipe can be made to be thin while maintaining the durability and elastic force, so that the whole weight of the tent pole can be reduced.

Further, according to the invention, both ends of the tent poles are connected with the connecting pipe so that the cross sections of the tent poles are not exposed. Accordingly, it is possible to prevent the user from contacting to the glass fiber of the cross section of the FRP tent pole even when the tent pole is made of FRP. In addition, it is possible to connect and assemble the tent poles having different diameters and materials by using the connecting pipes having different inner diameters.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. 

1. A connecting device of a pair of tent poles comprising: a first connecting pipe including one end having an inner diameter corresponding to an outer diameter of one tent pole and the other end forming a widened part having a widened diameter compared to one end, wherein an end of the one tent pole is inserted and fixed in one end of the first connecting pipe and an end of the other tent pole is connected to the widened part of the first connecting pipe.
 2. The connecting device as claimed in claim 1, further comprising a second connecting pipe including one end having an inner diameter corresponding to an outer diameter of the other tent pole and the other end forming a reduced part having a reduced outer diameter compared to the one end so as to correspond to an inner diameter of the widened part of the first connecting pipe, wherein an end of the other tent pole is inserted and fixed in one end of the second connecting pipe and the reduced part of the second connecting pipe is inserted and fixed in the widened part of the first connecting pipe.
 3. The connecting device as claimed in claim 1, wherein the one tent pole has a diameter smaller than the other tent pole and the widened part of the first connecting pipe has an inner diameter corresponding to an outer diameter of the other tent pole, and an end of the other tent pole is directly connected to the widened part of the first connecting pipe.
 4. The connecting device as claimed in claim 1, wherein the one tent pole has a diameter smaller than the other tent pole and the device further comprises: a second connecting pipe including one end having an inner diameter corresponding to an outer diameter of the other tent pole and the other end forming a reduced part having a diameter reduced to be equal to the widened part of the first connecting pipe; and a third connecting pipe having both ends inserted and fixed in the widened part of the first connecting pipe and the reduced part of the second connecting pipe, respectively.
 5. The connecting device as claimed in claim 1, wherein the tent poles have a same diameter, one end of the other tent pole is formed with a widened part having a diameter widened to be equal to the widened part of the first connecting pipe, and the connecting device further comprises a third connecting pipe having both ends inserted and fixed in the widened part of the first connecting pipe and the widened part of the other tent pole, respectively.
 6. The connecting device as claimed in claim 1, wherein the one tent pole has a diameter smaller than that of the other tent pole, one end of the other tent pole is formed with a reduced part having a diameter reduced to be equal to the widened part of the first connecting pipe, and the connecting device further comprises a third connecting pipe having both ends inserted and fixed in the widened part of the first connecting pipe and the reduced part of the other tent pole, respectively.
 7. The connecting device as claimed in claim 2, wherein a bending rigidity of the reduced part of the second connecting pipe is 60% or more of a bending rigidity of the widened part of the first connecting pipe.
 8. The connecting device as claimed in claim 4, wherein a bending rigidity of the reduced part of the second connecting pipe is 60% or more of a bending rigidity of the widened part of the first connecting pipe.
 9. The connecting device as claimed in claim 1, wherein one of the tent poles is made of fiber reinforced plastic (FRP) or carbon
 10. The connecting device as claimed in claim 9, wherein the connecting pipe is made of high strength aluminum. 